Locating objects in mobile computings

no location information
Extreme 2:
at any site
Extreme 1:
information at all sites
up-to-date and exact
Precision
Availability
Currency
At all sites
Exact location
At selective sites
Set of locations
Up-to-date
Out-of-date
Station
Base
Station
Base
Fixed
Host
Mbps to Gbps
Mobile
Host
Host
Mobile
Wireless LAN cell
Mobile

Host
1 Mbps
Mobile
Host
Fixed Network
9 Kbps
Wireless radio cell
Base
Host
Fixed
Station
Fixed
Host
Fixed
Host
Wireless radio cell
x
x
x
18
2
4 5
7
9
16
27262524
22

21
20191817
23
8
6
12
11
10
1514
13
1
0
3
x
x
x
x
18
18
18
18
the location databases
maintain pointers
the location databases
mobile user x
is at cell 18
x
entries for user x when
maintain actual locations
entries for user x when

(+)
(+) Support for locality
Increased number of operations (database operations
and communication messages)
(-)
(-) Increased load and storage requirements at higher-levels
No need for life-long numbering (no pre-assigned HLR)
16
2
4 5 9
27262524
22
21
20191817
23
8
6
12
11
10
1514
1
0
3
13
7
P1

P2
P3
P4
user x
IN
Parttion 1
Partition 2
Partition 3
Partition 4
user x
new location
2
4 5
7
9
16
27262524
22
21
20191817
23
8
6
12
11
10
1514
13
1

0
3
search procedure
forward bypass
pointer
reverse
bypass
pointer
s
t
user x
s t
P1
P2
P3
P4
Z1
Z2
Z3
users zones
(0, 2)
(-6, 1)
(0, 3)
source sink

16
old entries for x
new entries for x
2
4 5
7
9
27262524
22
21
20191817
23
8
6
12
11
10
1514
1
0
3
13
old location new location
user x
user x
Forwarding Pointer
level m
ts
16
x | 14

x | 14
x | 14
x | 17
x | 17
x | 14 x | 17 x | 17
2
4 5
7
9
27262524
22
21
20191817
23
8
6
12
11
10
1514
1
0
3
13
level m
x | 14
new entries for x
old entries for x
(this entry is not updated)
user x

old location
user x
new location
Forwarding Pointer